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General Aircraft: Tips & Techniques
Discussions on specific A/C building techniques.
cracked canopy
Biggles2
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Quebec, Canada
Joined: January 01, 2004
KitMaker: 7,600 posts
AeroScale: 121 posts
Posted: Monday, July 25, 2016 - 08:00 PM UTC
I have a through-and-through crack in a canopy. The crack goes right across glass sections. I know it'll never get repaired back to original, but how can I minimize the damage? Aircraft in question is CMK's Special Hobby 1/48 Focke Achgelis Fa 223E-0 helicopter. Kit has been OOP for a few years so requesting a replacement part is not going to happen.
moogieman
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United States
Joined: December 14, 2011
KitMaker: 12 posts
AeroScale: 11 posts
Posted: Monday, July 25, 2016 - 09:23 PM UTC
You didn't say where the crack was or how many panels it involves, but a couple of ideas came to mind (1) You could vacform a replacement canopy, but that's a pretty big canopy in 1/48, even if you did it in two sections- doable, but not an easy task! (2)Unless the crack is in the circular panel in the nose, you could carefully cut out the damaged panels and replace them with clear plastic that is the same thickness as the original canopy molding- since the Perspex panels on the -223's canopy are all trapezoidal or rectangular, this should be doable (3) If the circular panel in the nose is the damaged section, it gets a little harder- if the panel is flat, cut out the entire circular section and replace with flat clear stock; if that panel is curved, and off the top of my head, I don't remember if it is, then you can use a slightly curved clear piece- maybe from a plastic soda bottle? That's as far as my thinking takes me, I'm afraid. Good luck. I(Glad I have the 1/72 kit- it's a lot easier to fix!)

Mike
Biggles2
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Quebec, Canada
Joined: January 01, 2004
KitMaker: 7,600 posts
AeroScale: 121 posts
Posted: Tuesday, July 26, 2016 - 03:42 AM UTC
The thing is, it cracked the first time during masking because the plastic is thin and brittle. Any more pressure on it will cause it to completely crack in half, or crack again in a different place.
Joel_W
Staff MemberAssociate Editor
AUTOMODELER
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New York, United States
Joined: December 04, 2010
KitMaker: 11,666 posts
AeroScale: 7,410 posts
Posted: Tuesday, July 26, 2016 - 03:50 AM UTC
The only way to glue it is with Extra Thin as it doesn't flog clear plastic. Once really dry, you need to sand the joint starting with #400 grit, then 600. Then polish it with Micro Mesh pads from 4,000 up to 12,000. Finish off with a plastic polish like the Novus 3 system.
Joel
Namabiiru
Staff MemberAssociate Editor
MODEL SHIPWRIGHTS
#399
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Rhode Island, United States
Joined: March 05, 2014
KitMaker: 2,888 posts
AeroScale: 307 posts
Posted: Wednesday, July 27, 2016 - 10:44 PM UTC
Hmm,
My experience has been that even the Tamiya extra thin will cause fogging or spider-webbing in clear acrylic. I would instead recommend clear part glue, such as Testors. Since you say the parts are pretty brittle, sanding and polishing may not be much of an option. Rather, you might be able to spray a coat of Future on after gluing the pieces back together. Won't make the crack disappear, but hopefully less noticeable at least.

Biggles2
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Quebec, Canada
Joined: January 01, 2004
KitMaker: 7,600 posts
AeroScale: 121 posts
Posted: Wednesday, July 27, 2016 - 10:58 PM UTC
Thanks all for the tips.